STEICOmulti UDB is a highly vapour-permeable, windproof and weather-resistant membrane designed for external building envelopes. It can be used as a roof underlay / sarking membrane (including as a supplement to sarking boards), or as a windproof layer behind external wall build-ups. Thanks to its robust 3-layer construction and integrated self-adhesive sealing zones, it delivers reliable protection from wind and driving rain while still allowing the structure to dry safely outward.
Key Benefits
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Extremely vapour open (sd ≈ 0.02 m) – supports outward drying and moisture-safe construction
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Windproof + weather-resistant for roofs and external wall applications
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Two integrated self-adhesive zones for secure bonding and fast detailing
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Robust 3-layer coated PP non-woven fabric with high tear resistance
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W1 resistance to water penetration (including after artificial ageing)
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Outdoor exposure up to 12 weeks (during construction phase)
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Suitable as a temporary roof cover for up to 4 weeks (when correctly detailed)
Typical Uses
Roofing
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Sarking membrane / roof underlay
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Diffusion-open formwork membrane supporting breathable roof build-ups
External Walls
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Windproofing layer within breathable external wall systems (behind cladding / façade systems)
Refurbishment / Retrofit
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Can also function as an airtight layer within compatible refurbishment solutions, where detailing and continuity are correctly achieved
Installation Notes (Best Practice)
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Lay with the printed side facing the installer
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Install parallel to the eaves, starting from the bottom
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Maintain minimum 100mm overlaps
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Fix only within the overlap zone (e.g., staples/clips)
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Activate the self-adhesive strips only after fixing the sheet in position
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On roofs, secure with STEICOmulti nail tape and counter battens
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Where used as windproofing or airtightness, all joints/edges/penetrations must be bonded appropriately using STEICO system accessories
